3 Oct 2011

Manganese carbonyl calculation addition

Lab Experiment

Submitted by Adam R. Johnson, Harvey Mudd College

This is an addendum to the Manganese Carbonyl experiment (linked below).  In this part of the experiment, students carry out high level quantum mechanical calculations of reactants, intermediates, and products in order to determine which of two possible structures is correct.

Learning Goals: 

A student will learn modern computational methods as applied to an organometallic complex

a student will apply the results of a computational experiment to a real synthesis

Equipment needs: 

The exercise is written assuming access to a WebMO cluster, but could be readily modified for use on a local Gaussian/Spartan environment.  There are two related activities that are not showing up below so I am linking them here:


Implementation Notes: 

I have made this a required characterization method for my students who choose to do this experiment in my course.  As the theory required to get the "right" answer is high, I provide optimized input files and simply have the students calculate the energies, vibrations, and MOs.  This addendum is very strongly appealing for budding computational chemists, and is a good way for me to recruit joint thesis students to work on modeling inorganic systems for my research.  It is very helpful to have a computational chemist available to help with running the jobs the first time you do this, but it is not particularly taxing for the software.

Time Required: 
several hours for the computations, several more for analysis and writeup. This is done out of class.
Evaluation Methods: 

I usually have to work individually with students on this, but the payoff is high.  Once students see the light, they get really excited about it.  I look to make sure they are calculating the total energy of the reaction, have correctly identified the CO stretches and made some attempt to visualize the MOs.

Evaluation Results: 

students sometimes try to calcuate the reaction coordinate energy by only using the HOMO energy.  Students sometimes have a hard time finding the correct vibrational modes that relate to CO stretching

Creative Commons License: 
Creative Commons Licence

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